No action for recovery of any amount paid pursuant to this act shall be maintained in any court unless objections have been filed with the commission as herein provided. In any action for recovery of any payments made under this act the claimant shall be entitled to raise every relevant issue of law, but the commission’s findings of fact made pursuant to this act shall be prima facie evidence of the facts therein stated.

The following shall be deemed to be findings of fact of the commission within the meaning of this act: (a) Determinations of fact expressed in notices of assessments given pursuant to this act; (b) determinations of fact set out in those minutes of the commission which record the action of the commission in connection with making of the assessments and in passing upon objections thereto.